A small subset of genes that encode transcription factors are expressed at spatially restricted positions and times during vertebrate central nervous system (CNS) development. These "informative" transcription factors act singly and in combinations to regulate fate choice and subtype specification. The primary goal of Project by Ma is to build a comprehensive temporal/spatial map of transcription factor expression patterns in the developing mouse CNS. Our central hypothesis is that this transcription factor atlas will identify novel regulators of early cell fate choice in neural progenitors and later maturation of specialized neurons and glia. The most carefully annotated vertebrate genome - human- encodes approximately 1,600 known or putative transcription factors of all classes (homeodomain, nuclear hormone, zinc finger, etc). In preliminary work, we have i) identified murine homologues of all human transcription factor-encoding genes, ii) designed and generated PCR primer pairs for these genes, and iii) cloned approximately 75% (1200) of them into vectors suitable for in situ hybridization (ISH). Our study plan builds upon this and other preliminary groundwork. We have three specific aims: Aim 1 is to characterize the expression patterns of all transcription factor-encoding genes by ISH at key stages of forebrain, hindbrain, cerebellar and spinal cord development. Aim 2 is to catalogue the data into a searchable resource accessible to the general public via the web. The database will link ISH images to relevant annotation, accession numbers reagents, other vertebrate and invertebrate databases and human neurodevelopmental - neurodegenerative disease loci. Aim 3 is to test the central hypothesis. Towards this end, we will determine whether the atlas can be used to identify transcription factors that implement the actions of Olig and Ngn bHLH transcription factors on neuronal sub-type specification. The atlas will be scanned to identify transcription factors expressed in the Olig2 domain of spinal cord and the Ngn expression domain of the cortex. Candidate target genes will be culled by observation of aberrant expression in Olig2-/-and Ngn1/2-/- tissues, respectively and then assessed for biological function in chick neural tube assays. Aims 2 and 3 draw heavily upon the informatics and expression vector cores. The project as a whole will augment efforts in Projects by Greenberg and Stiles to identify Ngn target genes and co regulator proteins for Olig 1 and Olig2.